Throughout this application, various publications, patents, and published patent applications are referred to by an identifying citation. The disclosures of the publications, patents, and published patent applications referenced in this application are hereby incorporated by reference into the present disclosure to more fully describe the state of the art to which this invention pertains.
There has been considerable interest in recent years in developing high energy density batteries with lithium containing anodes. Lithium metal is particularly attractive as the anode active material of electrochemical cells because of its light weight and high energy density, compared, for example, to anode active materials, such as lithium intercalated carbon anodes, where the presence of non-electroactive materials increases the weight and volume of the anode, and thereby reduces the energy density of the cells. The use of lithium metal anodes, or those comprising mainly lithium metal, provides an opportunity to construct cells that are lighter in weight and have a higher energy density than cells such as lithium-ion, nickel metal hydride or nickel-cadmium cells. These features are highly desirable for batteries for portable electronic devices such as cellular telephones and laptop computers, as noted, for example, in Linden in Handbook of Batteries, 1995, 2nd Edition, chapter 14, pp. 75–76, and chapter 36, p.2, McGraw-Hill, New York and in U.S. Pat. No. 6,406,815 to Sandberg et al.
There is also a desire to use battery-operated devices in challenging environments, such as lower-temperature environments as, for example, environments encountered outdoors in winter. At temperatures well below room temperature, such as −10° C. to −20° C., many batteries have a significantly reduced discharge capacity. Reduction in discharge capacity at low temperatures is particularly severe in higher discharge rate applications, such as 0.2 C (C/5) or greater.
There has been considerable interest in recent years in developing high energy density cathode-active materials for use in high energy primary and secondary batteries with alkali-metal anode materials. Several types of cathode materials for the manufacture of thin-film lithium and sodium batteries are known and include cathode materials comprising sulfur-sulfur bonds, wherein high energy capacity and rechargeability are achieved from the electrochemical cleavage (via reduction) and reformation (via oxidation) of these bonds. Sulfur containing cathode materials, having sulfur-sulfur bonds, disclosed for use in lithium and sodium batteries comprise elemental sulfur, organo-sulfur, and carbon-sulfur compositions.
The choice of electrolyte for a particular cathode and anode combination depends on one or more of many factors, including: safety, cycle life, and chemical compatibility of the cathode and anode materials to the components of the electrolyte.